Apparatus for the control of highway crossing signals



July 24, 1962 A. E. DODD Filed Dec. 12, 1958 APPARATUS FOR THE CONTROLOF HIGHWAY CROSSING SIGNALS g; j; W v I1 5 2 312 12 4 10a 1 77H Z4\ I 14:1 g 25 I1 3*1446 TPZZ I IV 42 BHJJL 56L 40 W1 [3 W2 ymmmwe '52? ,54 B*lI l B 51 4 5: 0

Fhzymazz Copzfacs.

INVENTOR. flr'lzur E. Dada.

BY W

H15 HTTOW rear end of the train has vacated the crossing.

3,046,393 APPARATUS FOR THE CONTROL OF HIGH- WAY CROSSING SIGNALS ArthurE. Dodd, Edgewood, Pa., assignor to Westinghouse Air Brake Company,Wilmertling, Pa., a corporation of Pennsylvania Filed Dec. 12, 1958,SenNo. 779,948

7 Claims. ((Cl. 246130) My invention relates to apparatus for thecontrol of highway crossing signals, and particularly to novel andimproved apparatus for controlling the operation of a highway crossingsignal located at the intersection of a highway and a railway track overwhich trains pass in both directions.

In highway crossing signal systems of the type employed for a stretch oftrack over which trailic moves in both directions, directional controlmeans are employed to cause operation of the crossing signal whenever atrain approaches the crossing in either direction, and to preventoperation when the train recedes from the crossing. The directionalcontrol means operates to permit a resumption of the flow of vehiclesand pedestrian trafiic over the highway crossing a short time after theNormally, it is the practice to employ at the crossing a short trackcircuit usually referred to as an island track circuit and twoapproachitrack circuits one oneach approach side of the crossing. Theapproach track circuits are normally of a length suflicient to provideadequate warning whenever either approach section becomes occupied by atrain. When the train occupies the island track section at the crossing,the warning is continued.

While I am aware that it has been proposed heretofore to provide signalprotection at the intersection of a highway with a railway track overwhich trains operate in both directions, an object of my presentinvention is to provide a novel and improved highway crossing signalcontrol system of the class described.

Other objects and advantages of my invention will appear as thespecification progresses.

In practicing my invention, the above-mentioned objects of my inventionare attained by providing two approach track sections separated fromeach other by a crossing or island track section. Each approach tracksection has connected thereto one winding of an interlocking relay whichserves as the track relay for that section. The windings of theinterlocking relay are controlled by train movements in the respectiveapproach sections, and by a relay serving as a repeater of a track relayconnected to the island track section.

I shall describe one form of apparatus embodying my invention, and shallthen point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view of a preferred form ofapparatus embodying my invention.

Referring to the drawing, the reference characters 10 and 10a designatethe track rails of a stretch of railway track over which traflic movesin both directions, and which is intersected by a highway H. Locatedadjacent the intersection is a highway crossing signal S, which may beof any suitable type, but which is shown herein as an audible signal inthe form of an electric bell. The track rails 10 and 10a are divided bymeans of the usual insulated rail joints 12 into relatively longsections DE and F-G separated from each other by a relatively shortsection EF. Sections DE and 'FG will generally be of such lengths as toprovide users of the highway at the crossing with an adequate warningperiod upon the entrance of a train into the section. Section EF willgenerally be of such length as to completely include the intersection.

its rates i tent 3,646,393 Patented July 24, 1962 Section EF is providedwith a track circuit compri's'-' ing a suitable source of current, suchas'a track battery 14, connected across the rails at one'end of thesection, and a track relay designated by the reference character TR,connected across the section at the other end. Re lay TR is providedwith a front contact'lG for controlling the operation of a repeaterrelay TPR having a first en ergizing circuit which may extend frompositive terminal B of a suitable source of current such as a bat tery,not shown, over front contact 16 of relay TR, and through the winding ofrelay TPR to terminal N of the battery.

Section DE is provided witha'track circuit which may be traced from oneterminal of track battery 14 of section DE, through rail" 10, wire 18,the winding W1 of an interlocking'relay IRto be described, front contact20 of relay TPR, wire 22, and rail ltla to the other terminal of battery14.

Section FG is provided with a track circuit which may extend from oneterminal of track battery 14 of section F-G, through rail 10, wire 24,winding W2 of relay IR, front contact 26 of relay TPR, wire 28; and

rail liia to the other terminal of battery 14.

The interlocking relay IR, previously referred to, may be of anysuitable type, such as, for example; the relay covered by Letters Patentof the United States, No. 1,799,629, granted to William K. Lockhart andThomas J. OMeara on April 7, 1931, for InterlockingRelays, and assignedto the 'assignee of the present application; This type of relay is wellknown and ischaracterized by the fact that when theleft-hand winding W1becomes 'deenergized, the downward movement of the armature associatedwith winding W1 operates a mechanical locking detent which prevents thearmature associated with the right-hand winding W2 from dropping to "itsfull released position; that is, the armature associated with winding W2will be kept locked up inapproximately-its mid position, so that whenwinding W2 subsequently becomes de-' 'energizedduring the time windingW1 is still deenergized,

back contact 30 remains open. Similarly, if the righthand winding W2 isthe first to become deenergi'zed, then back contact 31 of winding W1 isprevented from closing when winding W1 becomes deenergized during theinterval that winding W2 remains deenergized. Relay'lR is also providedwith front contacts 32 and 34 associated with windings W1 and W2,respectively, which have what I shall term flagman adjustments. That isto say, each fiagman contact remains closed when its associated armatureis in its locked up position. However, each winding W1 and W2 whendeenergized before the subse quent deenergization of the other windingoperates to release all of its associated front and back contacts.

As will be explained hereinafter, the interlocking relay I'R functionsas directional means for preventing the op: eration of crossing signal Sby winding W1 or W2 when section DE or FG becomes occupied by a trainreceding from the intersection.

Relay TPR is provided with a second energizing circuit which may extendfrom terminal B of the battery, through flagman contacts 32 and 34,respectively, of winding W1 and W2, wire 36, and the winding of relayTPR to terminal Not the battery.

Signal S is energized over a circuit passing from terminal B of thebattery through three branch paths to wire 40, the operating element ofsignal S and to terminal N of the battery; the first path includingcontact 31 of winding W1 of relay IR, the second path including backcontact 42 of track relay TR, and the third path including contact 30 ofwinding W2. I

The apparatus, as shown in the accompanying drawing, is in its normalposition when sections DE, EF, and FG are unoccupied. In this condition,track relay TR is energized, repeater relay TPR is energized over bothof its above-traced energizing circuits, and windings W1 and W2 of relayIR are energized. Signal S is deenergized.

I shall now assume that an eastbound train, that is, a train moving fromleft to right in the drawing, enters section DE and shunts winding W1 ofrelay IR. Winding W1, therefore, becomes deenergized and releasescontact 31 and flagman contact 32 to full released positions, thereby,respectively, establishing the above-traced first branch path forenergizing the operating element of signal S, and interrupting thesecond named energizing circuit for repeater relay TPR. Signal S nowbecomes energized and exhibits its warning of the approach of the trainto highway users.

When the train enters section E--'F, relay TR is shunted and becomesdeenergized to open front contact 16 and close back contact 42, theclosing of contact 42 completing the above-traced second branch path forenergizing the operating element of signal S, thereby causing signal Sto continue to operate. The opening of contact 16 interrupts the firstnamed energizing circuit for relay TPR. Consequently, relay TPR becomesdeenergized. When this happens, contacts 20 and 26 of relay TPR bothopen. The opening of contact 20 of relay TPR at this time serves nouseful purpose since winding W1 remains shunted by the portion of thetrain occupying section DE. However, the opening of contact 26 of relayTPR interrupts the energizing circuit for winding W2 of relay IR so thatwinding W2 becomes deenergized and releases its contact 30 to its lockedup position. It is to be noted that to complete the energizing circuitfor winding W1, relay TPR must become energized and section DE mustagain be unoccupied.

When the train vacates section EF, and completely clears highway H,relay TR picks up over its energizing circuit to close front contact 16and to open back contact 42. The opening of back contact 42 of relay TRopens the second branch path in the energizing circuit for signal S, andthe closing of front contact 16 completes the previously mentioned firstenergizing circuit for relay TPR so that relay TPR becomes energized.Front contacts 20 and 26 of relay TPR now close. The closing of contact20 of relay TPR completes the previously traced circuit for winding W1so that winding W1 becomes energized. Front fiagman contact 32 ofwinding W1 now closes and back contact 31 opens. The closing of contact32 of winding W1 completes the second named energizing circuit for relayTPR whereas the opening of back contact 31 opens the first branch pathin the circuit for energizing signal S. Since contact '30 of winding W2is locked up to keep open the third branch path for operating signal S,signal S now becomes deenergized and ceases Ttoidisplay its warning.Although contact 26 of relay TPR is now closed, winding W2 remainsdeenergized since section F-G is occupied as the train recedes from theintersection.

When the train vacates section FG, winding W2 becomes energized, and theapparatus is returned to its normal condition.

The operation of the apparatus for a west-bound train is substantiallysimilar to the operation just described for an eastbound train as willbe readily apparent from an inspection of the drawing, and furtherdescription is believed unnecessary.

It should be noted that when one winding of the interlocking relaybecomes deenergized to release its contacts to their full releasedposition to complete a circuit for operating signal S, and, during theinterval section E-F is occupied, relay TPR becomes deenergized andoperates to prevent that winding of the interlocking relay fromsubsequently becoming energized. Simultaneously, relay TPR will operateto deenergize the other winding of the interlocking relay, therebyallowing the directional feature of the interlocking relay to beestablished. That is, when track section DE is occupied by an eastboundtrain, winding W1 becomes deenergized and the contacts controlled bywinding W1 release to their full released position. During thesubsequent presence of the train in track section EF, contact 20controlled by relay TPR releases to prevent winding W1 from againbecoming energized until the time that the train vacates track sectionEF, so that the armature controlled by winding W2 is released to itslocked up position prior to the armature controlled by winding W1 beingpicked up. Hence, the directional feature of the apparatus for trainsmoving in either direction over the crossing is insured.

It should further be pointed out that when the rails are accidentallyshunted by a crawler type tractor or similar vehicle using the highwayand moving over the crossing, relay TR will become deenergized. Theclosing of back contact 42 of relay TR will complete the second branchpath for energizing signal S, thereby causing the signal to operate. Theopening of front contact 16 of relay TR will open the above-traced firstenergizing circuit for relay TPR. However, relay TPR will be retainedenergized over its second pickup circuit including the series-connectedfiagman contacts controlled by windings W1 and W2 of interlocking relayIR. With relay TPR energized, and relay TR accidentally shunted and itscontact 16 released, windings W1 and W2 will remain energized over theirrespective pickup circuits including contacts 20 and 26 of relay TPR.The simultaneous release of the armature controlled by windings W1 andW2, which might cause one side of interlocking relay IR to be locked up"and thereby cause the approach section on that side to be insensitive toa train entering that approach section, is thus prevented. Thus,notwithstanding the presence of the vehicle in section EF which bridgesthe rails, windings W1 and W2 of relay IR remain energized and incondition for detecting the presence of a train entering either sectionDE or F-G. A train then entering either approach section prior to thetime the tractor ceases to shunt the rails, will, depending upon thedirection of traliic, cause either the first or second branch path forsignal S which is already operating to be completed and will continuethe operation of signal S to cause ample warning to be given to users ofthe highway. Subsequent to the time the tractor vacates the rails, atrain entering section DE or F--G in the direction of the crossing willcause operation of the signal in the manner described hereinabove sothat sufiicient time for warning the highway trafiic is atiorded. In allcases wherein a branch path for energizing signal S is completed,whether caused by unauthorized or accidental shunting of the rails bythe crawler-type vehicle or by a train, users of the highway willreasonably assume that a train is near or approaching the crossing andwill be warned not to pass over the track.

It should particularly be pointed out that as one advantage of myinvention, relays TR and TPR embodied herein may be of the type known inthe art as two-point relays, that is, a relay adapted for controllingonly two contacts. Two-point relays are normally small in overall size,and the use of such relays as contemplated would reduce the spacenecessary for housing the relays, and thereby provide an arrangementwhich is relatively inexpensive. The use of a two-point relay for relayTR is also favorable to fast shunting time which is desirable on anyisland track circuit.

Although I have herein shown and described only one form of apparatusembodying my invention, it is understood that various changes =andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination with a stretch of railway track divided into anintermediate track section separating first and second approach tracksections leading toward a highway intersecting said intermediatesection, a track relay for said intermediate section, a repeater relay,a

first pickup circuit for said repeater relay including a front contactof said track relay, an interlocking relay comprising first and secondwindings, a second pickup circuit for said repeater relay controlled bysaid first and second windings, a track circuit for said first approachsection including said first winding of said interlocking relay and afirst front cont-act of said repeater relay, a track circuit for saidsecond approach section including said second winding of saidinterlocking relay and a second front contact of said repeater relay, asignal at said intersection, and a circuit for energizing said signalincluding a contact controlled by said track relay and contactscontrolled separately by said first and second windings of saidinterlocking relay.

2. In combination, a stretch of railway track divided into first andsecond approach sections separated irom each other by an intermediatesection intersected by a highway, a track relay, a track circuit forsaid intermediate section including said track relay, an interlockingrelay comprising first and second windings, a repeater relay, a firstenergizing circuit for said repeater relay including a front contactcontrolled by said track relay, a second energizing circuit for saidrepeater relay including series-connected front contacts controlled bysaid first and second windings, a track circuit for said first approachsection including said first winding of said interlocking relay and afirst front contact controlled by said repeater relay, a track circuitfor said second approach section including said second winding of saidinterlocking relay and a second front contact controlled by saidrepeater relay, a signal at said intersection, and means individuallycontrolled by said first and second windings and by said track relay forcontrolling said signal.

3. In combination, a stretch of railway track divided into relativelylong first and second track sections separated by a relatively shortthird track section intersected by a highway, a signal adjacent saidintersection, a normally energized track relay 'for said third tracksection, a normally energized repeater relay energized over a firstcircuit including a front contact controlled by said track relay, aninterlocking relay comprising first and second windings, a secondcircuit for energizing said repeater relay including series-connectedfront contacts controlled by said first and second windings of saidinterlocking relay, a track circuit for said first track sectionincluding said first winding of said interlocking relay and a firstfront contact controlled by said repeater relay, a track circuit forsaid second track section including said second winding of saidinterlocking relay and a second front contact controlled by saidrepeater relay, and means separately controlled by said windings and bysaid track relay for controlling said signal.

4. In a signal system provided for a stretch of railway track dividedinto two approach track sections separated from each other by anintermediate section intersected by a highway, a signal adjacent saidintersection, a track relay, a track circuit for said intermediatesection including said track relay, a repeater relay, a first circuitfor energizing said repeater relay including means controlled by saidtrack relay, an interlocking relay comprising first and second windings,a track relay for each of said approach track sections comprising saidfirst and second windings of said interlocking relay, a pickup circuitfor said first winding of said interlocking relay including first meanscontrolled by said repeater relay, a pickup circuit for said secondwinding of said interlocking relay including second means controlled bysaid repeater relay, a second circuit for energizing said repeater relayinsaid track relay, an interlocking relay comprising first and secondwindings, a second pickup circuit for said repeater relay includingseries-connected flagman contacts controlled by said windings of saidinterlocking relay, said first winding of said interlocking relayconnected to said first approach track section through a first contactcontrolled by said repeater relay, said second winding of saidinterlocking relay connected to said second approach track sectionthrough a second front contact controlled by said repeater relay,whereby when only said third track section is occupied said first andsecond windings of said interlocking relay both remain energized, andmeans controlled by said first and second windings of said interlockingrelay and by said track relay for controlling said signal.

6. In combination, a stretch of railway track intersected by a highwayand divided into three successive track sections the middle one of whichseparates the outer track sections and includes the intersection, ahighway crossing signal at said intersection, an interlocking relaycomprising first and second windings each serving as a track relayconnected to one of said outer track sections, atrack circuit for saidmiddle track section including a track relay, a repeater relay havingparallel pickup circuits including respectively a front contactcontrolled by said track relay and series-connected front contactscontrolled by said first and second windings of said interlocking relay,a track circuit for each of said outer track sections including thewinding of said interlocking relay connected to the outer track sectionand a contact controlled by said repeater relay, and means separatelycontrolled by each of said windings and by said track relay controllingthe operation of said signal.

7. In a highway crossing control system for a stretch of track dividedinto first, second, and third successive track sections, a highwayintersecting said second track section and a signal at saidintersection, circuit means for detecting the occupancy of said secondtrack section by a railway vehicle, repeater means, a first energizingcircuit for said repeater means when said second track section isunoccupied including means controlled by said circuit means, aninterlocking relay having first and second windings, a track circuit forsaid first track section including said first winding of saidinterlocking relay and first means controlled by said repeater means, atrack circuit for said third track section including said second windingof said interlocking relay and second means controlled by said repeatermeans, a second energizing circuit for said repeater means includingmeans controlled by said first and second windings of said interlockingrelay, and means controlled by said first winding, said second windlng,and said train responsive means individually effective for controllingsaid signal.

References Cited in the file of this patent UNITED STATES PATENTS2,881,309 Fodge Apr. 7, 1,959

